1. Field of the Invention
The invention relates generally to safety valves and devices used within a wellbore.
2. Description of the Related Art
In the oil and gas industry, subsurface safety valves are used as a means of stopping the production of hydrocarbons in the event of an unexpected catastrophe or a planned shut down of a well. Most subsurface safety valves are hydraulically controlled from the surface facility by connecting a hydraulic control line to surface pumping equipment. Application of pressure at the surface is transmitted to the safety valve to open the device. Subsurface safety valves are typically installed into the well as a part of the production tubing string. Accordingly, these safety valves are typically referred to as tubing retrievable safety valves (TRSVs). In the event that the TRSV fails or stops functioning properly, it is possible to install a smaller safety valve into the interior diameter of the existing TRSV by running the smaller valve into the production tubing on wireline. The smaller installed valve is referred to as a wireline insert safety valve (WLSV). The WLSV operates off of the hydraulic pressure of the TRSV. Before running the WLSV into the TRSV, it is necessary to create a communication chamber between the TRSV and the wellbore. Several tools or methods can be used to accomplish fluid communication with the hydraulic chamber of the TRSV. Once communication is established, the WLSV is landed into the TRSV. A set of seals located on the upper portion and the lower portion of the WLSV land above and below the TRSV. The seals prevent the hydraulic fluid from escaping into the wellbore and allow the WLSV to operate off of the hydraulic control line of the TRSV.
It is problematic to utilize a wireline insert safety valve where the TRSV uses electrical power rather than hydraulic power to be actuated. There is no mechanism for transmitting hydraulic power to the wireline insert valve. In addition, if the WLSV is electrically powered, it is difficult to transmit electrical power to the WLSV in a reliable manner. Downhole environments are filled with debris and are extremely corrosive environments. Solids can build up on exposed areas of a downhole valve, including electrical contacts. An electrical plug or port for electrically mating the TRSV and WLSV would likely become exposed and filled with debris to make an electrical connection difficult, if not impossible.